Effect of selenite and selenised yeast supplementation on selenium concentration of Finnish organic milk – a farm study.

Experiment was conducted at 15 certified organic dairy farms in Eastern Finland during spring 2008. Farms were allocated to three balanced groups according annual milk yield, herd size and housing system. Three types of selenium (Se) supplementations: selenium yeast (SY), sodium selenite (SS) or their (50:50) combination (SYS) was used. Daily Se doses were adjusted according to milk yield basis (average 3 mg/d). Experimental model was 3 X 3 Latin square, consisting from 3 experiment periods. The length of each period was 28 days. RehuRaisio provided experimental feeds. In the end of each period bulk-tank milk samples were collected and analysed for Se at MTT Agrifood Research Finland. The Se supplementation form was crucial for milk Se concentration (P<0.001), when Se concentration of basic fodder was extreme low (<0.01 mg/kg DM). SS (n=15) resulted to milk Se concentration of 0.012 mg/kg, but SYS (n=15) resulted to 1.9-fold and SY (n=14) to 2.3-fold higher milk Se concentrations

Shock waves in the dissipative Toda lattice

We consider the propagation of a shock wave (SW) in the damped Toda lattice. The SW is a moving boundary between two semi-infinite lattice domains with different densities. A steadily moving SW may exist if the damping in the lattice is represented by an ``inner'' friction, which is a discrete analog of the second viscosity in hydrodynamics. The problem can be considered analytically in the continuum approximation, and the analysis produces an explicit relation between the SW's velocity and the densities of the two phases. Numerical simulations of the lattice equations of motion demonstrate that a stable SW establishes if the initial velocity is directed towards the less dense phase; in the opposite case, the wave gradually spreads out. The numerically found equilibrium velocity of the SW turns out to be in a very good agreement with the analytical formula even in a strongly discrete case. If the initial velocity is essentially different from the one determined by the densities (but has the correct sign), the velocity does not significantly alter, but instead the SW adjusts itself to the given velocity by sending another SW in the opposite direction.Comment: 10 pages in LaTeX, 5 figures available upon regues

Velocity correlations and diffusion during sedimentation

We study the dynamics of sedimenting non-Brownian particles under steady-state conditions in two-dimensional geometry. We concentrate on the autocorrelation functions of the velocity fluctuations and the corresponding memory functions and diffusion coefficients as functions of ΦV for small but finite Reynolds numbers. For the numerical simulations we have chosen the model of Schwarzer [Phys. Rev. E 52, 6461 (1995)] where a continuum liquid phase is coupled through Stokesian friction to a discrete particle phase with volume fraction ΦV. We find that the steady-state velocity fluctuations are spatially highly anisotropic and the correlation functions parallel to gravity have nonexponential time dependence similar to that of purely dissipative systems with strong interactions. The corresponding memory functions also show nontrivial behavior. Diffusion along the direction of gravity is much faster than perpendicular to it, with the anisotropy decreasing as either the Reynolds number or the volume fraction increases.Peer reviewe

Sedimentation dynamics of spherical particles in confined geometries

We study the steady-state dynamics of sedimenting non-Brownian particles in confined geometries with full hydrodynamic interactions at small but finite Reynolds numbers. We employ extensive computer simulations using a method where a continuum liquid phase is coupled through Stokesian friction to a discrete particle phase. In particular, we consider a sedimentation box which is otherwise periodic except that it is confined by two parallel walls parallel to gravity with a spacing Lx. By systematically varying Lx we explore the change in dynamics from a quasi-two-dimensional (2D) case to a three-dimensional case. We find that in such confined geometries there is a depletion of particle number density at the walls for small volume fractions, while for large volume fractions there is an excess number of particles at the walls. For the average sedimentation velocity, we find that the Richardson-Zaki law is well obeyed but the decrease of the velocity for dilute systems is slower for smaller values of Lx. We study the anisotropy of the velocity fluctuations and find that in the direction of gravity there is excellent agreement with the predicted scaling with respect to Lx. We also find that the behavior of the corresponding diffusion coefficients as a function of Lx is qualitatively different in the direction parallel to gravity and perpendicular to it. In the quasi-2D limit where particles block each other, the velocity fluctuations behave differently from the other confined systems.Peer reviewe

Collective Effects in Settling of Spheroids under Steady-State Sedimentation

We study the settling dynamics of non-Brownian prolate spheroids under steady-state sedimentation. We consider the case of moderate particle Reynolds numbers properly taking into account the hydrodynamic effects. For small volume fractions, we find an orientational transition of the spheroids, characterized by enhanced density fluctuations. Around the transition, the average settling velocity has a maximum which may even exceed the terminal velocity of a single spheroid, in accordance with experiments.Peer reviewe

Progressive motion of an ac-driven kink in an annular damped system

A novel dynamical effect is presented: systematic drift of a topological soliton in ac-driven weakly damped systems with periodic boundary conditions. The effect is demonstrated in detail for a long annular Josephson junction. Unlike earlier considered cases of the ac-driven motion of fluxons (kinks), in the present case the long junction is_spatially uniform_. Numerical simulations reveal that progressive motion of the fluxon commences if the amplitude of the ac drive exceeds a threshold value. The direction of the motion is randomly selected by initial conditions, and a strong hysteresis is observed. An analytical approach to the problem is based on consideration of the interaction between plasma waves emitted by the fluxon under the action of the ac drive and the fluxon itself, after the waves complete round trip in the annular junction. The analysis predicts instability of the zero-average-velocity state of the fluxon interacting with its own radiation tails, provided that the drive's amplitude exceeds an explicitly found threshold. The predicted threshold amplitude strongly depends on the phase shift gained by the wave after the round trip. A very similar dependence is found in the simulations, testifying to the relevance of the analytical consideration.Comment: revtex text file and five eps figure files. Physical Review E, in pres

Characterisation of Herbage from Temperate Organic Pastures

Grazing is an essential part of organic dairy farming systems. Although the nutritive value of herbage and herbage availability determine the intake and nutrient supply for grazing cows, the composition of typical herbage from organic pastures has been unclear

Wittgenstein's Thought Experiments and Relativity Theory

In this paper, I discuss the similarity between Wittgenstein’s use of thought experiments and Relativity Theory. I begin with introducing Wittgenstein’s idea of “thought experiments” and a tentative classification of different kinds of thought experiments in Wittgenstein’s work. Then, after presenting a short recap of some remarks on the analogy between Wittgenstein’s point of view and Einstein’s, I suggest three analogies between the status of Wittgenstein’s mental experiments and Relativity theory: the topics of time dilation, the search for invariants, and the role of measuring tools in Special Relativity. This last point will help to better define Wittgenstein’s idea of description as the core of his philosophical enterprise

Review on possible gravitational anomalies

This is an updated introductory review of 2 possible gravitational anomalies that has attracted part of the Scientific community: the Allais effect that occur during solar eclipses, and the Pioneer 10 spacecraft anomaly, experimented also by Pioneer 11 and Ulysses spacecrafts. It seems that, to date, no satisfactory conventional explanation exist to these phenomena, and this suggests that possible new physics will be needed to account for them. The main purpose of this review is to announce 3 other new measurements that will be carried on during the 2005 solar eclipses in Panama and Colombia (Apr. 8) and in Portugal (Oct.15).Comment: Published in 'Journal of Physics: Conferences Series of the American Institute of Physics'. Contribution for the VI Mexican School on Gravitation and Mathematical Physics "Approaches to Quantum Gravity" (Playa del Carmen, Quintana Roo, Mexico, Nov. 21-27, 2004). Updates to this information will be posted in http://www.lsc-group.phys.uwm.edu/~xavier.amador/anomalies.htm